Despite the potential benefits of looking young, we predicted that older adults who attempt to look younger than they are would threaten the distinctiveness of young adults' social identity and, for this reason, such “passers” would be evaluated negatively. In three experiments we found that both male and female young adults negatively evaluated older adults who attempt to look younger compared to older adults who do not attempt to do so. Both male and female targets who attempt to look younger were evaluated negatively (Experiment 2), and these negative evaluations were a function of experienced threat to young adults' social identities (Experiment 3). Older adults may attempt to look young to avoid age-based prejudice or conform to existing standards, but doing so can result in negative evaluations by younger people. Copyright © 2010 John Wiley & Sons, Ltd.